Distributed strain sensing devices with high precision and high spatial resolution are widely used in the livelihoods and national defense security fields, such as structural health monitoring of aircraft, spacecraft, ships, defense equipments, industrial equipments, bridge culverts and other key parts, and a distributed strain sensing with high precision and high spatial resolution can be achieved by using the Rayleigh scattering spectral shift of a single mode fiber in optical frequency domain reflection. However, in practical applications, the temperature and the strain changing at the same time will cause Rayleigh scattering spectral shift, i.e., a cross sensitivity problem. Therefore, it is required to adopt a new method to overcome the cross sensitivity problem.